1. Field of the Invention
The present invention pertains to a non-blocking multicast switching network for a multiplexed source.
2. Description of the Related Art
Traditionally, an N1×N2 Clos multicast network consists of three stages of switch modules. It has r1 switch modules of size n1×m in the input stage, m switch modules of size r1×r2 in the middle stage, and r2 switch modules of size m×n2 in the output stage. Here, as shown in FIG. 1, total number of input lines N1 is n1×r1, and total number of input lines N2 is n2×r2. In such a network, there is exactly one link between every two switch modules in two consecutive stages, and each switch module is assumed to be multicast-capable. The conventional technology has demonstrated that when m takes certain values, the three-stage Clos network has full multicast capability in a non-blocking manner.
Patent Reference 1: Japanese Unexamined Patent Application Publication No. 2007-504772
Recently, as the new technology develops, more powerful switching elements are commercially available. In such a switch, each port of the switch can simultaneously support multiple data streams from independent sources. We call this type of switch multi-source switches. In general, an s×s multi-source multicast switch has s input ports and s output ports, and each port has k independent links. The switch can connect from any input link to any set of output links. We can simply call the switch an s×s k-source switch. The switch can function as a sk×sk ordinary multicast switch. In fact, the internal implementation of such a switch is packet switching. For example, letting k=5, an s×s multi-source switch with 10G bandwidth on each port is equivalent to an sk×sk ordinary switch with 2G bandwidth on each link.
However, in the conventional technology, refinement of the number of the middle stage switches in a Clos network having full multicast capability for multi-source in a non-blocking manner has not been disclosed, thereby causing high cost. Moreover, an algorithm for addition or deletion of connections to the existing multicast tree has not been disclosed, and the addition or deletion of connections could not be carried out without loss of data.